This invention relates to clutches and in particular to clutches used to couple gear wheels to associated shafts in a vehicle transmission in order to engage selected drive ratios.
Such clutches are frequently arranged to be able to operate under load to provide a so-called "powershift" transmission in which ratio changes can be made without loss of driving torque through the transmission and without the operation of any associated main drive clutch. Frequently, such clutches are arranged in a double clutch arrangement positioned between two gear wheels with one clutch of the arrangement arranged to couple one gear to an associated shaft and the other clutch arranged alternatively to couple the other gear wheel to the same shaft.
Powershift transmissions are traditionally relatively bulky and expensive due to the relatively large size and complexity of existing ratio engaging clutches.